An IGBT (insulated gate bipolar transistor) with high emitter side charge carrier density has low on-state voltage drop (VCEON) and low switching-off losses, since at turn off most charge carriers are removed at low collector-to-emitter voltages (VCE). High emitter side charge carrier density can be achieved using trench cell geometry and/or by forming a potential barrier within the drift zone of the IGBT device (e.g. an n-type hole potential barrier for an npnp IGBT with n-type drift zone and p-type body). The barrier layer is typically formed by an implantation and annealing process performed before the gate trenches are formed. The depth of the barrier layer within the drift zone is limited by the implantation energy, implantation dose, implantation profile and subsequent diffusion processes. Also, the height of the body region may be reduced if the potential barrier layer is formed too shallow in the drift zone and/or if the implantation dose is too high and diffusion processes are too long. A reduced-height body region results in a shorter channel region, which can induce short channel effects such as high off-state leakage current, impact ionization, velocity saturation/mobility degradation, punch through, channel length modulation, etc. Hence, there is a need for semiconductor devices with improved barrier layers and corresponding methods of manufacture.